apt-pkg/contrib/fileutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: fileutl.cc,v 1.42 2002/09/14 05:29:22 jgg Exp $
   4 /* ######################################################################
   5
   6    File Utilities
   7
   8    CopyFile - Buffered copy of a single file
   9    GetLock - dpkg compatible lock file manipulation (fcntl)
  10
  11    Most of this source is placed in the Public Domain, do with it what
  12    you will
  13    It was originally written by Jason Gunthorpe <jgg@debian.org>.
  14    FileFd gzip support added by Martin Pitt <martin.pitt@canonical.com>
  15
  16    The exception is RunScripts() it is under the GPLv2
  17
  18    ##################################################################### */
  19                                                                         /*}}}*/
  20 // Include Files                                                        /*{{{*/
  21 #include <apt-pkg/fileutl.h>
  22 #include <apt-pkg/strutl.h>
  23 #include <apt-pkg/error.h>
  24 #include <apt-pkg/sptr.h>
  25 #include <apt-pkg/configuration.h>
  26
  27 #include <apti18n.h>
  28
  29 #include <cstdlib>
  30 #include <cstring>
  31 #include <cstdio>
  32
  33 #include <iostream>
  34 #include <unistd.h>
  35 #include <fcntl.h>
  36 #include <sys/stat.h>
  37 #include <sys/types.h>
  38 #include <sys/time.h>
  39 #include <sys/wait.h>
  40 #include <dirent.h>
  41 #include <signal.h>
  42 #include <errno.h>
  43 #include <set>
  44 #include <algorithm>
  45                                                                         /*}}}*/
  46
  47 using namespace std;
  48
  49 // RunScripts - Run a set of scripts from a configuration subtree       /*{{{*/
  50 // ---------------------------------------------------------------------
  51 /* */
  52 bool RunScripts(const char *Cnf)
  53 {
  54    Configuration::Item const *Opts = _config->Tree(Cnf);
  55    if (Opts == 0 || Opts->Child == 0)
  56       return true;
  57    Opts = Opts->Child;
  58
  59    // Fork for running the system calls
  60    pid_t Child = ExecFork();
  61
  62    // This is the child
  63    if (Child == 0)
  64    {
  65       if (chdir("/tmp/") != 0)
  66          _exit(100);
  67
  68       unsigned int Count = 1;
  69       for (; Opts != 0; Opts = Opts->Next, Count++)
  70       {
  71          if (Opts->Value.empty() == true)
  72             continue;
  73
  74          if (system(Opts->Value.c_str()) != 0)
  75             _exit(100+Count);
  76       }
  77       _exit(0);
  78    }
  79
  80    // Wait for the child
  81    int Status = 0;
  82    while (waitpid(Child,&Status,0) != Child)
  83    {
  84       if (errno == EINTR)
  85          continue;
  86       return _error->Errno("waitpid","Couldn't wait for subprocess");
  87    }
  88
  89    // Restore sig int/quit
  90    signal(SIGQUIT,SIG_DFL);
  91    signal(SIGINT,SIG_DFL);
  92
  93    // Check for an error code.
  94    if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
  95    {
  96       unsigned int Count = WEXITSTATUS(Status);
  97       if (Count > 100)
  98       {
  99          Count -= 100;
 100          for (; Opts != 0 && Count != 1; Opts = Opts->Next, Count--);
 101          _error->Error("Problem executing scripts %s '%s'",Cnf,Opts->Value.c_str());
 102       }
 103
 104       return _error->Error("Sub-process returned an error code");
 105    }
 106
 107    return true;
 108 }
 109                                                                         /*}}}*/
 110
 111 // CopyFile - Buffered copy of a file                                   /*{{{*/
 112 // ---------------------------------------------------------------------
 113 /* The caller is expected to set things so that failure causes erasure */
 114 bool CopyFile(FileFd &From,FileFd &To)
 115 {
 116    if (From.IsOpen() == false || To.IsOpen() == false)
 117       return false;
 118
 119    // Buffered copy between fds
 120    SPtrArray<unsigned char> Buf = new unsigned char[64000];
 121    unsigned long Size = From.Size();
 122    while (Size != 0)
 123    {
 124       unsigned long ToRead = Size;
 125       if (Size > 64000)
 126          ToRead = 64000;
 127
 128       if (From.Read(Buf,ToRead) == false ||
 129           To.Write(Buf,ToRead) == false)
 130          return false;
 131
 132       Size -= ToRead;
 133    }
 134
 135    return true;
 136 }
 137                                                                         /*}}}*/
 138 // GetLock - Gets a lock file                                           /*{{{*/
 139 // ---------------------------------------------------------------------
 140 /* This will create an empty file of the given name and lock it. Once this
 141    is done all other calls to GetLock in any other process will fail with
 142    -1. The return result is the fd of the file, the call should call
 143    close at some time. */
 144 int GetLock(string File,bool Errors)
 145 {
 146    // GetLock() is used in aptitude on directories with public-write access
 147    // Use O_NOFOLLOW here to prevent symlink traversal attacks
 148    int FD = open(File.c_str(),O_RDWR | O_CREAT | O_NOFOLLOW,0640);
 149    if (FD < 0)
 150    {
 151       // Read only .. cant have locking problems there.
 152       if (errno == EROFS)
 153       {
 154          _error->Warning(_("Not using locking for read only lock file %s"),File.c_str());
 155          return dup(0);       // Need something for the caller to close
 156       }
 157
 158       if (Errors == true)
 159          _error->Errno("open",_("Could not open lock file %s"),File.c_str());
 160
 161       // Feh.. We do this to distinguish the lock vs open case..
 162       errno = EPERM;
 163       return -1;
 164    }
 165    SetCloseExec(FD,true);
 166
 167    // Aquire a write lock
 168    struct flock fl;
 169    fl.l_type = F_WRLCK;
 170    fl.l_whence = SEEK_SET;
 171    fl.l_start = 0;
 172    fl.l_len = 0;
 173    if (fcntl(FD,F_SETLK,&fl) == -1)
 174    {
 175       if (errno == ENOLCK)
 176       {
 177          _error->Warning(_("Not using locking for nfs mounted lock file %s"),File.c_str());
 178          return dup(0);       // Need something for the caller to close
 179       }
 180       if (Errors == true)
 181          _error->Errno("open",_("Could not get lock %s"),File.c_str());
 182
 183       int Tmp = errno;
 184       close(FD);
 185       errno = Tmp;
 186       return -1;
 187    }
 188
 189    return FD;
 190 }
 191                                                                         /*}}}*/
 192 // FileExists - Check if a file exists                                  /*{{{*/
 193 // ---------------------------------------------------------------------
 194 /* */
 195 bool FileExists(string File)
 196 {
 197    struct stat Buf;
 198    if (stat(File.c_str(),&Buf) != 0)
 199       return false;
 200    return true;
 201 }
 202                                                                         /*}}}*/
 203 // DirectoryExists - Check if a directory exists and is really one      /*{{{*/
 204 // ---------------------------------------------------------------------
 205 /* */
 206 bool DirectoryExists(string const &Path)
 207 {
 208    struct stat Buf;
 209    if (stat(Path.c_str(),&Buf) != 0)
 210       return false;
 211    return ((Buf.st_mode & S_IFDIR) != 0);
 212 }
 213                                                                         /*}}}*/
 214 // CreateDirectory - poor man's mkdir -p guarded by a parent directory  /*{{{*/
 215 // ---------------------------------------------------------------------
 216 /* This method will create all directories needed for path in good old
 217    mkdir -p style but refuses to do this if Parent is not a prefix of
 218    this Path. Example: /var/cache/ and /var/cache/apt/archives are given,
 219    so it will create apt/archives if /var/cache exists - on the other
 220    hand if the parent is /var/lib the creation will fail as this path
 221    is not a parent of the path to be generated. */
 222 bool CreateDirectory(string const &Parent, string const &Path)
 223 {
 224    if (Parent.empty() == true || Path.empty() == true)
 225       return false;
 226
 227    if (DirectoryExists(Path) == true)
 228       return true;
 229
 230    if (DirectoryExists(Parent) == false)
 231       return false;
 232
 233    // we are not going to create directories "into the blue"
 234    if (Path.find(Parent, 0) != 0)
 235       return false;
 236
 237    vector<string> const dirs = VectorizeString(Path.substr(Parent.size()), '/');
 238    string progress = Parent;
 239    for (vector<string>::const_iterator d = dirs.begin(); d != dirs.end(); ++d)
 240    {
 241       if (d->empty() == true)
 242          continue;
 243
 244       progress.append("/").append(*d);
 245       if (DirectoryExists(progress) == true)
 246          continue;
 247
 248       if (mkdir(progress.c_str(), 0755) != 0)
 249          return false;
 250    }
 251    return true;
 252 }
 253                                                                         /*}}}*/
 254 // CheckDirectory - ensure that the given directory exists              /*{{{*/
 255 // ---------------------------------------------------------------------
 256 /* a small wrapper around CreateDirectory to check if it exists and to
 257    remove the trailing "/apt/" from the parent directory if needed */
 258 bool CheckDirectory(string const &Parent, string const &Path)
 259 {
 260    if (DirectoryExists(Path) == true)
 261       return true;
 262
 263    size_t const len = Parent.size();
 264    if (len > 5 && Parent.find("/apt/", len - 6, 5) == len - 5)
 265    {
 266       if (CreateDirectory(Parent.substr(0,len-5), Path) == true)
 267          return true;
 268    }
 269    else if (CreateDirectory(Parent, Path) == true)
 270       return true;
 271
 272    return false;
 273 }
 274                                                                         /*}}}*/
 275 // GetListOfFilesInDir - returns a vector of files in the given dir     /*{{{*/
 276 // ---------------------------------------------------------------------
 277 /* If an extension is given only files with this extension are included
 278    in the returned vector, otherwise every "normal" file is included. */
 279 std::vector<string> GetListOfFilesInDir(string const &Dir, string const &Ext,
 280                                         bool const &SortList, bool const &AllowNoExt)
 281 {
 282    std::vector<string> ext;
 283    ext.reserve(2);
 284    if (Ext.empty() == false)
 285       ext.push_back(Ext);
 286    if (AllowNoExt == true && ext.empty() == false)
 287       ext.push_back("");
 288    return GetListOfFilesInDir(Dir, ext, SortList);
 289 }
 290 std::vector<string> GetListOfFilesInDir(string const &Dir, std::vector<string> const &Ext,
 291                                         bool const &SortList)
 292 {
 293    // Attention debuggers: need to be set with the environment config file!
 294    bool const Debug = _config->FindB("Debug::GetListOfFilesInDir", false);
 295    if (Debug == true)
 296    {
 297       std::clog << "Accept in " << Dir << " only files with the following " << Ext.size() << " extensions:" << std::endl;
 298       if (Ext.empty() == true)
 299          std::clog << "\tNO extension" << std::endl;
 300       else
 301          for (std::vector<string>::const_iterator e = Ext.begin();
 302               e != Ext.end(); ++e)
 303             std::clog << '\t' << (e->empty() == true ? "NO" : *e) << " extension" << std::endl;
 304    }
 305
 306    std::vector<string> List;
 307    Configuration::MatchAgainstConfig SilentIgnore("Dir::Ignore-Files-Silently");
 308    DIR *D = opendir(Dir.c_str());
 309    if (D == 0)
 310    {
 311       _error->Errno("opendir",_("Unable to read %s"),Dir.c_str());
 312       return List;
 313    }
 314
 315    for (struct dirent *Ent = readdir(D); Ent != 0; Ent = readdir(D))
 316    {
 317       // skip "hidden" files
 318       if (Ent->d_name[0] == '.')
 319          continue;
 320
 321       // check for accepted extension:
 322       // no extension given -> periods are bad as hell!
 323       // extensions given -> "" extension allows no extension
 324       if (Ext.empty() == false)
 325       {
 326          string d_ext = flExtension(Ent->d_name);
 327          if (d_ext == Ent->d_name) // no extension
 328          {
 329             if (std::find(Ext.begin(), Ext.end(), "") == Ext.end())
 330             {
 331                if (Debug == true)
 332                   std::clog << "Bad file: " << Ent->d_name << " → no extension" << std::endl;
 333                if (SilentIgnore.Match(Ent->d_name) == false)
 334                   _error->Notice("Ignoring file '%s' in directory '%s' as it has no filename extension", Ent->d_name, Dir.c_str());
 335                continue;
 336             }
 337          }
 338          else if (std::find(Ext.begin(), Ext.end(), d_ext) == Ext.end())
 339          {
 340             if (Debug == true)
 341                std::clog << "Bad file: " << Ent->d_name << " → bad extension »" << flExtension(Ent->d_name) << "«" << std::endl;
 342             if (SilentIgnore.Match(Ent->d_name) == false)
 343                _error->Notice("Ignoring file '%s' in directory '%s' as it has an invalid filename extension", Ent->d_name, Dir.c_str());
 344             continue;
 345          }
 346       }
 347
 348       // Skip bad filenames ala run-parts
 349       const char *C = Ent->d_name;
 350       for (; *C != 0; ++C)
 351          if (isalpha(*C) == 0 && isdigit(*C) == 0
 352              && *C != '_' && *C != '-') {
 353             // no required extension -> dot is a bad character
 354             if (*C == '.' && Ext.empty() == false)
 355                continue;
 356             break;
 357          }
 358
 359       // we don't reach the end of the name -> bad character included
 360       if (*C != 0)
 361       {
 362          if (Debug == true)
 363             std::clog << "Bad file: " << Ent->d_name << " → bad character »"
 364                << *C << "« in filename (period allowed: " << (Ext.empty() ? "no" : "yes") << ")" << std::endl;
 365          continue;
 366       }
 367
 368       // skip filenames which end with a period. These are never valid
 369       if (*(C - 1) == '.')
 370       {
 371          if (Debug == true)
 372             std::clog << "Bad file: " << Ent->d_name << " → Period as last character" << std::endl;
 373          continue;
 374       }
 375
 376       // Make sure it is a file and not something else
 377       string const File = flCombine(Dir,Ent->d_name);
 378       struct stat St;
 379       if (stat(File.c_str(),&St) != 0 || S_ISREG(St.st_mode) == 0)
 380       {
 381          if (Debug == true)
 382             std::clog << "Bad file: " << Ent->d_name << " → stat says not a good file" << std::endl;
 383          continue;
 384       }
 385
 386       if (Debug == true)
 387          std::clog << "Accept file: " << Ent->d_name << " in " << Dir << std::endl;
 388       List.push_back(File);
 389    }
 390    closedir(D);
 391
 392    if (SortList == true)
 393       std::sort(List.begin(),List.end());
 394    return List;
 395 }
 396                                                                         /*}}}*/
 397 // SafeGetCWD - This is a safer getcwd that returns a dynamic string    /*{{{*/
 398 // ---------------------------------------------------------------------
 399 /* We return / on failure. */
 400 string SafeGetCWD()
 401 {
 402    // Stash the current dir.
 403    char S[300];
 404    S[0] = 0;
 405    if (getcwd(S,sizeof(S)-2) == 0)
 406       return "/";
 407    unsigned int Len = strlen(S);
 408    S[Len] = '/';
 409    S[Len+1] = 0;
 410    return S;
 411 }
 412                                                                         /*}}}*/
 413 // flNotDir - Strip the directory from the filename                     /*{{{*/
 414 // ---------------------------------------------------------------------
 415 /* */
 416 string flNotDir(string File)
 417 {
 418    string::size_type Res = File.rfind('/');
 419    if (Res == string::npos)
 420       return File;
 421    Res++;
 422    return string(File,Res,Res - File.length());
 423 }
 424                                                                         /*}}}*/
 425 // flNotFile - Strip the file from the directory name                   /*{{{*/
 426 // ---------------------------------------------------------------------
 427 /* Result ends in a / */
 428 string flNotFile(string File)
 429 {
 430    string::size_type Res = File.rfind('/');
 431    if (Res == string::npos)
 432       return "./";
 433    Res++;
 434    return string(File,0,Res);
 435 }
 436                                                                         /*}}}*/
 437 // flExtension - Return the extension for the file                      /*{{{*/
 438 // ---------------------------------------------------------------------
 439 /* */
 440 string flExtension(string File)
 441 {
 442    string::size_type Res = File.rfind('.');
 443    if (Res == string::npos)
 444       return File;
 445    Res++;
 446    return string(File,Res,Res - File.length());
 447 }
 448                                                                         /*}}}*/
 449 // flNoLink - If file is a symlink then deref it                        /*{{{*/
 450 // ---------------------------------------------------------------------
 451 /* If the name is not a link then the returned path is the input. */
 452 string flNoLink(string File)
 453 {
 454    struct stat St;
 455    if (lstat(File.c_str(),&St) != 0 || S_ISLNK(St.st_mode) == 0)
 456       return File;
 457    if (stat(File.c_str(),&St) != 0)
 458       return File;
 459
 460    /* Loop resolving the link. There is no need to limit the number of
 461       loops because the stat call above ensures that the symlink is not
 462       circular */
 463    char Buffer[1024];
 464    string NFile = File;
 465    while (1)
 466    {
 467       // Read the link
 468       int Res;
 469       if ((Res = readlink(NFile.c_str(),Buffer,sizeof(Buffer))) <= 0 ||
 470           (unsigned)Res >= sizeof(Buffer))
 471           return File;
 472
 473       // Append or replace the previous path
 474       Buffer[Res] = 0;
 475       if (Buffer[0] == '/')
 476          NFile = Buffer;
 477       else
 478          NFile = flNotFile(NFile) + Buffer;
 479
 480       // See if we are done
 481       if (lstat(NFile.c_str(),&St) != 0)
 482          return File;
 483       if (S_ISLNK(St.st_mode) == 0)
 484          return NFile;
 485    }
 486 }
 487                                                                         /*}}}*/
 488 // flCombine - Combine a file and a directory                           /*{{{*/
 489 // ---------------------------------------------------------------------
 490 /* If the file is an absolute path then it is just returned, otherwise
 491    the directory is pre-pended to it. */
 492 string flCombine(string Dir,string File)
 493 {
 494    if (File.empty() == true)
 495       return string();
 496
 497    if (File[0] == '/' || Dir.empty() == true)
 498       return File;
 499    if (File.length() >= 2 && File[0] == '.' && File[1] == '/')
 500       return File;
 501    if (Dir[Dir.length()-1] == '/')
 502       return Dir + File;
 503    return Dir + '/' + File;
 504 }
 505                                                                         /*}}}*/
 506 // SetCloseExec - Set the close on exec flag                            /*{{{*/
 507 // ---------------------------------------------------------------------
 508 /* */
 509 void SetCloseExec(int Fd,bool Close)
 510 {
 511    if (fcntl(Fd,F_SETFD,(Close == false)?0:FD_CLOEXEC) != 0)
 512    {
 513       cerr << "FATAL -> Could not set close on exec " << strerror(errno) << endl;
 514       exit(100);
 515    }
 516 }
 517                                                                         /*}}}*/
 518 // SetNonBlock - Set the nonblocking flag                               /*{{{*/
 519 // ---------------------------------------------------------------------
 520 /* */
 521 void SetNonBlock(int Fd,bool Block)
 522 {
 523    int Flags = fcntl(Fd,F_GETFL) & (~O_NONBLOCK);
 524    if (fcntl(Fd,F_SETFL,Flags | ((Block == false)?0:O_NONBLOCK)) != 0)
 525    {
 526       cerr << "FATAL -> Could not set non-blocking flag " << strerror(errno) << endl;
 527       exit(100);
 528    }
 529 }
 530                                                                         /*}}}*/
 531 // WaitFd - Wait for a FD to become readable                            /*{{{*/
 532 // ---------------------------------------------------------------------
 533 /* This waits for a FD to become readable using select. It is useful for
 534    applications making use of non-blocking sockets. The timeout is
 535    in seconds. */
 536 bool WaitFd(int Fd,bool write,unsigned long timeout)
 537 {
 538    fd_set Set;
 539    struct timeval tv;
 540    FD_ZERO(&Set);
 541    FD_SET(Fd,&Set);
 542    tv.tv_sec = timeout;
 543    tv.tv_usec = 0;
 544    if (write == true)
 545    {
 546       int Res;
 547       do
 548       {
 549          Res = select(Fd+1,0,&Set,0,(timeout != 0?&tv:0));
 550       }
 551       while (Res < 0 && errno == EINTR);
 552
 553       if (Res <= 0)
 554          return false;
 555    }
 556    else
 557    {
 558       int Res;
 559       do
 560       {
 561          Res = select(Fd+1,&Set,0,0,(timeout != 0?&tv:0));
 562       }
 563       while (Res < 0 && errno == EINTR);
 564
 565       if (Res <= 0)
 566          return false;
 567    }
 568
 569    return true;
 570 }
 571                                                                         /*}}}*/
 572 // ExecFork - Magical fork that sanitizes the context before execing    /*{{{*/
 573 // ---------------------------------------------------------------------
 574 /* This is used if you want to cleanse the environment for the forked
 575    child, it fixes up the important signals and nukes all of the fds,
 576    otherwise acts like normal fork. */
 577 pid_t ExecFork()
 578 {
 579    // Fork off the process
 580    pid_t Process = fork();
 581    if (Process < 0)
 582    {
 583       cerr << "FATAL -> Failed to fork." << endl;
 584       exit(100);
 585    }
 586
 587    // Spawn the subprocess
 588    if (Process == 0)
 589    {
 590       // Setup the signals
 591       signal(SIGPIPE,SIG_DFL);
 592       signal(SIGQUIT,SIG_DFL);
 593       signal(SIGINT,SIG_DFL);
 594       signal(SIGWINCH,SIG_DFL);
 595       signal(SIGCONT,SIG_DFL);
 596       signal(SIGTSTP,SIG_DFL);
 597
 598       set<int> KeepFDs;
 599       Configuration::Item const *Opts = _config->Tree("APT::Keep-Fds");
 600       if (Opts != 0 && Opts->Child != 0)
 601       {
 602          Opts = Opts->Child;
 603          for (; Opts != 0; Opts = Opts->Next)
 604          {
 605             if (Opts->Value.empty() == true)
 606                continue;
 607             int fd = atoi(Opts->Value.c_str());
 608             KeepFDs.insert(fd);
 609          }
 610       }
 611
 612       // Close all of our FDs - just in case
 613       for (int K = 3; K != 40; K++)
 614       {
 615          if(KeepFDs.find(K) == KeepFDs.end())
 616             fcntl(K,F_SETFD,FD_CLOEXEC);
 617       }
 618    }
 619
 620    return Process;
 621 }
 622                                                                         /*}}}*/
 623 // ExecWait - Fancy waitpid                                             /*{{{*/
 624 // ---------------------------------------------------------------------
 625 /* Waits for the given sub process. If Reap is set then no errors are
 626    generated. Otherwise a failed subprocess will generate a proper descriptive
 627    message */
 628 bool ExecWait(pid_t Pid,const char *Name,bool Reap)
 629 {
 630    if (Pid <= 1)
 631       return true;
 632
 633    // Wait and collect the error code
 634    int Status;
 635    while (waitpid(Pid,&Status,0) != Pid)
 636    {
 637       if (errno == EINTR)
 638          continue;
 639
 640       if (Reap == true)
 641          return false;
 642
 643       return _error->Error(_("Waited for %s but it wasn't there"),Name);
 644    }
 645
 646
 647    // Check for an error code.
 648    if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
 649    {
 650       if (Reap == true)
 651          return false;
 652       if (WIFSIGNALED(Status) != 0)
 653       {
 654          if( WTERMSIG(Status) == SIGSEGV)
 655             return _error->Error(_("Sub-process %s received a segmentation fault."),Name);
 656          else
 657             return _error->Error(_("Sub-process %s received signal %u."),Name, WTERMSIG(Status));
 658       }
 659
 660       if (WIFEXITED(Status) != 0)
 661          return _error->Error(_("Sub-process %s returned an error code (%u)"),Name,WEXITSTATUS(Status));
 662
 663       return _error->Error(_("Sub-process %s exited unexpectedly"),Name);
 664    }
 665
 666    return true;
 667 }
 668                                                                         /*}}}*/
 669
 670 // FileFd::Open - Open a file                                           /*{{{*/
 671 // ---------------------------------------------------------------------
 672 /* The most commonly used open mode combinations are given with Mode */
 673 bool FileFd::Open(string FileName,OpenMode Mode, unsigned long Perms)
 674 {
 675    Close();
 676    Flags = AutoClose;
 677    switch (Mode)
 678    {
 679       case ReadOnly:
 680       iFd = open(FileName.c_str(),O_RDONLY);
 681       break;
 682
 683       case ReadOnlyGzip:
 684       iFd = open(FileName.c_str(),O_RDONLY);
 685       if (iFd > 0) {
 686          gz = gzdopen (iFd, "r");
 687          if (gz == NULL) {
 688              close (iFd);
 689              iFd = -1;
 690          }
 691       }
 692       break;
 693
 694       case WriteAtomic:
 695       {
 696          Flags |= Replace;
 697          char *name = strdup((FileName + ".XXXXXX").c_str());
 698          TemporaryFileName = string(mktemp(name));
 699          iFd = open(TemporaryFileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 700          free(name);
 701          break;
 702       }
 703
 704       case WriteEmpty:
 705       {
 706          struct stat Buf;
 707          if (lstat(FileName.c_str(),&Buf) == 0 && S_ISLNK(Buf.st_mode))
 708             unlink(FileName.c_str());
 709          iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_TRUNC,Perms);
 710          break;
 711       }
 712
 713       case WriteExists:
 714       iFd = open(FileName.c_str(),O_RDWR);
 715       break;
 716
 717       case WriteAny:
 718       iFd = open(FileName.c_str(),O_RDWR | O_CREAT,Perms);
 719       break;
 720
 721       case WriteTemp:
 722       unlink(FileName.c_str());
 723       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 724       break;
 725    }
 726
 727    if (iFd < 0)
 728       return _error->Errno("open",_("Could not open file %s"),FileName.c_str());
 729
 730    this->FileName = FileName;
 731    SetCloseExec(iFd,true);
 732    return true;
 733 }
 734
 735 bool FileFd::OpenDescriptor(int Fd, OpenMode Mode, bool AutoClose)
 736 {
 737    Close();
 738    Flags = (AutoClose) ? FileFd::AutoClose : 0;
 739    iFd = Fd;
 740    if (Mode == ReadOnlyGzip) {
 741       gz = gzdopen (iFd, "r");
 742       if (gz == NULL) {
 743          if (AutoClose)
 744             close (iFd);
 745          return _error->Errno("gzdopen",_("Could not open file descriptor %d"),
 746                               Fd);
 747       }
 748    }
 749    this->FileName = "";
 750    return true;
 751 }
 752                                                                         /*}}}*/
 753 // FileFd::~File - Closes the file                                      /*{{{*/
 754 // ---------------------------------------------------------------------
 755 /* If the proper modes are selected then we close the Fd and possibly
 756    unlink the file on error. */
 757 FileFd::~FileFd()
 758 {
 759    Close();
 760 }
 761                                                                         /*}}}*/
 762 // FileFd::Read - Read a bit of the file                                /*{{{*/
 763 // ---------------------------------------------------------------------
 764 /* We are carefull to handle interruption by a signal while reading
 765    gracefully. */
 766 bool FileFd::Read(void *To,unsigned long Size,unsigned long *Actual)
 767 {
 768    int Res;
 769    errno = 0;
 770    if (Actual != 0)
 771       *Actual = 0;
 772
 773    do
 774    {
 775       if (gz != NULL)
 776          Res = gzread(gz,To,Size);
 777       else
 778          Res = read(iFd,To,Size);
 779       if (Res < 0 && errno == EINTR)
 780          continue;
 781       if (Res < 0)
 782       {
 783          Flags |= Fail;
 784          return _error->Errno("read",_("Read error"));
 785       }
 786
 787       To = (char *)To + Res;
 788       Size -= Res;
 789       if (Actual != 0)
 790          *Actual += Res;
 791    }
 792    while (Res > 0 && Size > 0);
 793
 794    if (Size == 0)
 795       return true;
 796
 797    // Eof handling
 798    if (Actual != 0)
 799    {
 800       Flags |= HitEof;
 801       return true;
 802    }
 803
 804    Flags |= Fail;
 805    return _error->Error(_("read, still have %lu to read but none left"),Size);
 806 }
 807                                                                         /*}}}*/
 808 // FileFd::Write - Write to the file                                    /*{{{*/
 809 // ---------------------------------------------------------------------
 810 /* */
 811 bool FileFd::Write(const void *From,unsigned long Size)
 812 {
 813    int Res;
 814    errno = 0;
 815    do
 816    {
 817       if (gz != NULL)
 818          Res = gzwrite(gz,From,Size);
 819       else
 820          Res = write(iFd,From,Size);
 821       if (Res < 0 && errno == EINTR)
 822          continue;
 823       if (Res < 0)
 824       {
 825          Flags |= Fail;
 826          return _error->Errno("write",_("Write error"));
 827       }
 828
 829       From = (char *)From + Res;
 830       Size -= Res;
 831    }
 832    while (Res > 0 && Size > 0);
 833
 834    if (Size == 0)
 835       return true;
 836
 837    Flags |= Fail;
 838    return _error->Error(_("write, still have %lu to write but couldn't"),Size);
 839 }
 840                                                                         /*}}}*/
 841 // FileFd::Seek - Seek in the file                                      /*{{{*/
 842 // ---------------------------------------------------------------------
 843 /* */
 844 bool FileFd::Seek(unsigned long To)
 845 {
 846    int res;
 847    if (gz)
 848       res = gzseek(gz,To,SEEK_SET);
 849    else
 850       res = lseek(iFd,To,SEEK_SET);
 851    if (res != (signed)To)
 852    {
 853       Flags |= Fail;
 854       return _error->Error("Unable to seek to %lu",To);
 855    }
 856
 857    return true;
 858 }
 859                                                                         /*}}}*/
 860 // FileFd::Skip - Seek in the file                                      /*{{{*/
 861 // ---------------------------------------------------------------------
 862 /* */
 863 bool FileFd::Skip(unsigned long Over)
 864 {
 865    int res;
 866    if (gz)
 867       res = gzseek(gz,Over,SEEK_CUR);
 868    else
 869       res = lseek(iFd,Over,SEEK_CUR);
 870    if (res < 0)
 871    {
 872       Flags |= Fail;
 873       return _error->Error("Unable to seek ahead %lu",Over);
 874    }
 875
 876    return true;
 877 }
 878                                                                         /*}}}*/
 879 // FileFd::Truncate - Truncate the file                                 /*{{{*/
 880 // ---------------------------------------------------------------------
 881 /* */
 882 bool FileFd::Truncate(unsigned long To)
 883 {
 884    if (gz)
 885    {
 886       Flags |= Fail;
 887       return _error->Error("Truncating gzipped files is not implemented (%s)", FileName.c_str());
 888    }
 889    if (ftruncate(iFd,To) != 0)
 890    {
 891       Flags |= Fail;
 892       return _error->Error("Unable to truncate to %lu",To);
 893    }
 894
 895    return true;
 896 }
 897                                                                         /*}}}*/
 898 // FileFd::Tell - Current seek position                                 /*{{{*/
 899 // ---------------------------------------------------------------------
 900 /* */
 901 unsigned long FileFd::Tell()
 902 {
 903    off_t Res;
 904    if (gz)
 905      Res = gztell(gz);
 906    else
 907      Res = lseek(iFd,0,SEEK_CUR);
 908    if (Res == (off_t)-1)
 909       _error->Errno("lseek","Failed to determine the current file position");
 910    return Res;
 911 }
 912                                                                         /*}}}*/
 913 // FileFd::Size - Return the size of the file                           /*{{{*/
 914 // ---------------------------------------------------------------------
 915 /* */
 916 unsigned long FileFd::Size()
 917 {
 918    //TODO: For gz, do we need the actual file size here or the uncompressed length?
 919    struct stat Buf;
 920    if (fstat(iFd,&Buf) != 0)
 921       return _error->Errno("fstat","Unable to determine the file size");
 922    return Buf.st_size;
 923 }
 924                                                                         /*}}}*/
 925 // FileFd::Close - Close the file if the close flag is set              /*{{{*/
 926 // ---------------------------------------------------------------------
 927 /* */
 928 bool FileFd::Close()
 929 {
 930    bool Res = true;
 931    if ((Flags & AutoClose) == AutoClose)
 932    {
 933       if (gz != NULL) {
 934          int const e = gzclose(gz);
 935          // gzdopen() on empty files always fails with "buffer error" here, ignore that
 936          if (e != 0 && e != Z_BUF_ERROR)
 937             Res &= _error->Errno("close",_("Problem closing the gzip file %s"), FileName.c_str());
 938       } else
 939          if (iFd > 0 && close(iFd) != 0)
 940             Res &= _error->Errno("close",_("Problem closing the file %s"), FileName.c_str());
 941    }
 942
 943    if ((Flags & Replace) == Replace && iFd >= 0) {
 944       if (rename(TemporaryFileName.c_str(), FileName.c_str()) != 0)
 945          Res &= _error->Errno("rename",_("Problem renaming the file %s to %s"), TemporaryFileName.c_str(), FileName.c_str());
 946
 947       FileName = TemporaryFileName; // for the unlink() below.
 948    }
 949
 950    iFd = -1;
 951    gz = NULL;
 952
 953    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
 954        FileName.empty() == false)
 955       if (unlink(FileName.c_str()) != 0)
 956          Res &= _error->WarningE("unlnk",_("Problem unlinking the file %s"), FileName.c_str());
 957
 958
 959    return Res;
 960 }
 961                                                                         /*}}}*/
 962 // FileFd::Sync - Sync the file                                         /*{{{*/
 963 // ---------------------------------------------------------------------
 964 /* */
 965 bool FileFd::Sync()
 966 {
 967 #ifdef _POSIX_SYNCHRONIZED_IO
 968    if (fsync(iFd) != 0)
 969       return _error->Errno("sync",_("Problem syncing the file"));
 970 #endif
 971    return true;
 972 }
 973                                                                         /*}}}*/